According to the Wildlife Conservation Society (WCS), which had representatives observing the crush in China, about 96 elephants a day are killed illegally in Africa, largely because of the demand for their ivory. Much of that ivory ends up in China, where it is carved and sold domestically or abroad.

There are an estimated 500,000 elephants left in Africa, and poaching them is a $10 billion business that draws international crime syndicates and terrorist groups.

International trade in ivory was outlawed in 1990, but poaching continues to fuel a thriving black market. Some legal sales of ivory stockpiles have also been allowed, which critics say has made enforcement more difficult. (Read "Ivory Worship" in National Geographic magazine.)

Over the years, a number of countries have participated in high-profile burns or crushes of confiscated ivory, including Kenya, Gabon, the Philippines, and the U.S.

Although ivory is seized at national borders, sale of ivory products remains legal domestically in the U.S. and China. Because the material is difficult to identify, date, and track, legal markets incentivize traffickers to try to cheat the system, critics such as the WCS say.

According to a WCS statement, "In the U.S., WCS seeks national and state moratoria on all purchases and sales of ivory, and in Asia WCS assists concerned citizens who wish to educate their countrymen and women through social media about the lethal cost of ivory to Africa's elephants."

Zhao Shucong, director of China's State Forestry Administration, admitted to the Washington Post that ivory smuggling is "still raging" and said that China is "in urgent need of sincere collaboration with different countries and international organizations" in its attempts at dealing with the problem.